The Difference Between Keto and Low Carb Diets

Often people who claim to follow a ketogenic diet are actually following a low carb diet. This article will help clear up confusion on the differences between low carb and ketogenic diets and discuss the benefits of a well-formulated ketogenic diet as compared to a traditional low carb diet.

Low Carb Defined

Although the definition varies across the literature, a low-carbohydrate (low carb) diet tends to be classified as a diet containing less than 30% of calories from carbohydrates (1,2). While most low carb diets contain 50-150 grams of carbs per day, some athletes adhering to this type of diet have over 200 grams of carbs due to their higher caloric requirements.

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The rest of the calories contained in the diet usually come from high protein intake and moderate-to-high fat intake.

The Difference in Ketogenic Diets

Unlike the typical “low-carb” diet, a well-formulated ketogenic diet follows a high-fat, moderate-protein,  low-carb approach, e.g. 75% fat, 20% protein, and 5% carbohydrate. A ketogenic diet typically allows about 20-50 grams of carbohydrates per day (3).

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This macronutrient profile allows the body to start producing and to eventually utilize an alternative fuel source known as ketones (4). This process is analogous to changing your car’s fuel source to something longer lasting, more readily available, and more sustainable overall.

The Main Problem with “Low-Carb”

A common mistake with ketogenic dieting is going “low-carb” but still having a high protein and moderate fat intake. As discussed in previous articles, carbohydrate restriction is essential for a ketogenic diet. However, the high-fat, moderate-protein component is equally as important. If protein intake is too high on a low carb, low-calorie diet, your body could increase glucose production through a process known as gluconeogenesis. More research is needed in this area as it relates to ketogenic dieting.  Ultimately, this could prevent your body achieving a state of nutritional ketosis.

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Benefits of a Ketogenic Diet vs. “Low-Carb”

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While calorie balance may be a critical factor in determining weight loss or weight gain, a “low-carb” diet can negatively affect one’s quality of life and diet outcome. This effect is largely due to the resulting inability to achieve “ketosis” or provide great deal of carbohydrates for energy.  Most people here are essentially “stuck in the middle” between two options.

There are several benefits of a ketogenic diet over a regular “low-carb” diet approach:

Greater Fat Loss and Lean Mass Retention

Ketogenic diets are protein sparing, meaning that your body will not burn amino acids for energy, but instead use ketones as a primary energy source (5,6).

On a low carb diet, protein and amino acids are likely to be used for energy due to a shortage of glucose from carbohydrates. Instead, the body may utilize gluconeogenesis to produce glucose for energy. As a result, “low-carb” diets can result in more lean mass loss during weight loss.

A study by Young (7) compared: 1) a low carb diet (100 grams), 2) a lower-carbohydrate diet (60 grams), and 3) a ketogenic diet (30 grams).  Subjects had all of their meals prepared for them and each consumed the same amount of protein. The subjects in the ketogenic group lost significantly more body fat and maintained more lean mass than the subjects in the other two conditions. This was likely due to higher ketone levels in the 30-gram group and their protein sparing effect.

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Improved Brain Function

The trials people encounter during “low-carb” dieting are unpredictable, ranging from mild discomfort and fuzzy-headedness to full blown flu-like symptoms like nausea, fatigue, mental fog, headaches, cramps, diarrhea, etc. When truly in ketosis, energy levels are typically higher and more stable, increased focus and concentration can be experienced, and any “flu-like” systems subside once one has adapted to the diet. These benefits likely stem from the fact that ketone levels are actually elevated on a ketogenic diet compared to a traditional low carb approach.

Reduced Hunger and Improved Satiety

Low carb diets have been shown to improve satiety in comparison to a standard Western diet (8), mainly because of the increased level of fats and protein in the diet. Decreasing carbs and increasing protein and fats can help to reduce fluctuations in blood sugar, promote fatty acid metabolism, and provide satiety or fullness through interactions of digestive hormones.

When someone is on a ketogenic diet, the body is fueled by a long-lasting, sustainable, and readily available fuel source – ketones. This reserve source of fuel is extremely large regardless of how lean an individual is.  Compare that to running on glucose from carbohydrates or protein, which are available only in the limited amount we can store and can consume in our diet. Following the consumption of a large carbohydrate-containing meal, individuals tend to eventually become hypoglycemic, which triggers greater hunger and leaves individuals in the roller coaster in search of more food. However, on a ketogenic diet, appetite hormones like leptin and ghrelin appear to favor satiety and keep you fuller longer.

The macronutrient compositions of traditional low-carb diets typically do not meet the requirements of a true ketogenic diet. When a ketogenic diet is strictly adhered to, the benefits include more favorable body composition, enhanced brain function, and increased satiety.

Keto Conclusions

  • Low carbohydrate diets can be beneficial, but it is important to differentiate between ketogenic and low carbohydrate diets due to the uniqueness of being in a state of ketosis.
  • A ketogenic diet is a very low carbohydrate diet that contains a moderate amount of protein and high levels of fat, which allows the body to shift fuel sources and start producing ketones.
  • Low carbohydrate diets can restrict carbohydrates similarly to a ketogenic diet.
  • Ketogenic diets can improve body composition (decreased body fat, retention of lean mass) to a greater extent than low carbohydrate dieting alone.
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References

  1. Bueno, N. B., de Melo, I. S. V., de Oliveira, S. L., & da Rocha Ataide, T. (2013). Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition, 110(07), 1178-1187.
  2. Nordmann, A. J., Nordmann, A., Briel, M., Keller, U., Yancy, W. S., Brehm, B. J., & Bucher, H. C. (2006). Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Archives of internal medicine, 166(3), 285-293.
  3. Freeman, J. M., Kossoff, E. H., & Hartman, A. L. (2007). The ketogenic diet: one decade later. Pediatrics, 119(3), 535-543.
  4. Westman, E. C., Yancy, W. S., Olsen, M. K., Dudley, T., & Guyton, J. R. (2006). Effect of a low-carbohydrate, ketogenic diet program compared to a low-fat diet on fasting lipoprotein subclasses. International journal of cardiology, 110(2), 212-216.
  5. Manninen, A. H. (2006). Very-low-carbohydrate diets and preservation of muscle mass. Nutrition & metabolism, 3(1), 1.
  6. Vazquez, J. A., & Adibi, S. A. (1992). Protein sparing during treatment of obesity: ketogenic versus nonketogenic very low calorie diet. Metabolism,41(4), 406-414.
  7. Young, C. M., Scanlan, S. S., Im, H. S., & Lutwak, L. (1971). Effect on body composition and other parameters in obese young men of carbohydrate level of reduction diet. The American journal of clinical nutrition, 24(3), 290-296.
  8. Gibbons, C., Caudwell, P., Finlayson, G., Webb, D. L., Hellström, P. M., Näslund, E., & Blundell, J. E. (2013). Comparison of postprandial profiles of ghrelin, active GLP-1, and total PYY to meals varying in fat and carbohydrate and their association with hunger and the phases of satiety. The Journal of Clinical Endocrinology & Metabolism, 98(5), E847-E855.

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